Science in agriculture
Most farms are family farms. “In 2010 of all the farms in the United States with at least $1 million in revenues, 88 percent were family farms, and they accounted for 79 percent of production. Large-scale farmers today are sophisticated businesspeople who use GPS equipment to guide their combines, biotechnology to boost their yields, and futures contracts to hedge their risk. They are also pretty rich.” —Chrystia Freeland. August 1, 2012. “The Triumph of the Family Farm.” The Atlantic.
Innovation without science
Before getting into the role of science in agricultural progress we should first remark that much innovation can, has, and will be done without the involvement of scientists, universities, or even experimentation. Great inventors and perpetual tinkers often have no need for a scientific background and might actually find scientists to hold them back. From the time of hunter-gatherers until today humans have sought to make their lives easier by coming up with new ideas. Given the importance of agriculture and the heavy physical burden it placed on our ancestors, it is likely they were constantly trying to think of better ways to farm.
Someone, likely a female, had the idea of deliberately putting seeds into the ground with the intention of harvesting it later. Millennia later, we have agronomy. Another, perhaps a male, thought it a good idea to keep livestock cornered in a canyon instead of having to track them for miles and miles on a hunt. Millennia later, we have livestock.
From those two great ideas, fast forward thousands of years later to the 10th century AD, where two great ideas led to what might legitimately be called an agricultural revolution. These are the heavy-wheeled plow and the horse-collar and horseshoe. These were not suddenly invented, as the wheeled plow existed as early as the 5th century in the Slavic world, but it became particularly popular later. The horse-collar and horseshoe allowed farmers to pull implements with a horse, which was much faster than ox.(A1)
There was no “science” driving these innovations. Science as we know it didn’t exist, and the education that did exist was focused almost exclusively on foreign languages, rhetoric, religion and history. The future seemed irrelevant to the highest forms of education, and engineering was more of a trade, learned through apprenticeship and experience. They nevertheless improved upon agriculture, and without the physical sciences, we would improve it as well. That said, agriculture has accomplished things that would be impossible without the modern world’s education system focus on the physical sciences.
A familiar agricultural revolution
The word “agricultural revolution” gets thrown around a lot (especially by me). Typically when people say “agricultural revolution” they are either referring to the Neolithic period when people learned to farm, or the 19th century when mechanization in agriculture began.
I want to talk first about an agricultural revolution in ancient China, around the 1st century BC. The technologies used today may be vastly different from the ancient Chinese, the social conditions necessary for technological progress have not. China existed under good leaders around this time. These rulers were not that different from other rulers. They sought power, hegemony over a large area, and riches. What was different is that they understood how wealth is created.
- First, they kept low taxes on land, so that farmers had the incentive to improve their productivity, because they kept a sizeable portion of the extra amount they produced.
- Second, market prices were allowed to fluctuate (for the most part), so that market forces could dictate to farmers what should be planted, and where. If more rice was needed, the price of rice would rise, farmers would see a profit opportunity, and planting more rice in response, prices would fall. Sometimes the best cure for high prices is high prices.
- Thirdly, the government subsidized the acquisition and dissemination of knowledge, resembling the modern land grant university system in the U.S.. Scholars wrote textbooks and encyclopedias of agriculture, general research was encouraged, and scholars were sent out into the country to teach the peasant farmers what they have learned. These scholars also learned from the peasants, bringing back information on how the peasants farmed as well as new plant species.
- Finally, the government invested in large-scale public infrastructure like irrigation and grain storage.
The results were astounding. Farmers learned how to
- double-crop.
- treat seeds so that they would not germinate until the next planting.
- better irrigate rice, and recirculate water.
- use mulch to keep the ground from drying.
- use cover crops.
- produce better iron implements.
- employ new fermentation and pickling technologies.(A2)
You might say that the U.S. reinvented the wheel in 19th century with the creation of land grant universities, experiment stations, and extension research, as its core philosophy closely resembles that in ancient China. .
The U.S. Land Grant System
In his 1796 presidential address George Washington called for a board of agriculture at the federal level that would encourage experimentation with farming methods. It is not worth the effort for any one farm to set aside land for experimentation. Some like Edward Ruffin did it anyway, but most experiments would end in failure and would result in a financial loss, and so would yield little return for the ordinary farmer. Nevertheless, most all farmers recognize the value of other people experimenting and sharing their results. Some regions established agricultural clubs where farmers could convene to trade ideas and share the results of their experiments. It made sense for all farmers to spend a little money funding an experimental farm, and then sharing the knowledge gained with the world.
George Washington’s idea never went anywhere for same reason the idea was never seriously considered until the Civil War: concerns about the balance between state and federal power. Washington’s peers felt that it would be an unconstitutional reach of federal power, and was an idea that should be left up for the states themselves to accomplish.
Around 1840 there began a serious debate on the extent to which scientific experimentation even could improve farming. One might say that modern agronomy began in 1840 Germany with the publication of Justus von Liebig’s Organic Chemistry and its Applications. Throughout the 19th century Germany would be the leader in agricultural science, where its 70+ government-funded experimental farms gave them a hegemony in the knowledge of crop production. Liebig constructed a theory of plant growth that suggested a field could remain in perpetual fertility by chemically analyzing the soil and restoring the proper balance of nutrients, and Germany's experimental farms suggested that theory was correct.
Liebig spelled out the necessary plant nutrients as being nitrogen, phosphate, and potash, and other micronutrients of lesser importance— this idea is accepted fact today. He thought that phosphorus was the most important nutrient for growth and set about finding ways of adding it to the soil, like by adding sulfuric acid bone. Not much attention was paid to nitrogen, as he believed enough was made available from rain and snow that there was little need to acquire artificial sources.
A Purdue University agronomist would prove him wrong on nitrogen, when he spelled out the word “nitrogen” on the lawn in front of the dean’s office with nitrogen. As the grass receiving the nitrogen surged above the grass that did not, the writing was clear, and the dean was convinced. The world remains convinced, as today, half of the nitrogen in your body was taken from the sky and made into a fertilizer using a big factory and advanced chemistry.(P1)
Back to Liebig. His work and the other experiments in Britain got many in the agricultural community excited about the idea that science was going to usher in a revolution in farming. People latched onto the idea before science could really produce anything, and soon chemists began to really understand the complexity of the soil, and this understanding suggested that chemical fertilizer would not be easy to manufacture. This split the agricultural community into two groups: one who believed science would eventually deliver results if given the proper funding and the other who believed that investing in science was not worth it.
Interest in “scientific agriculture” encouraged a number of businesses to begin selling artificial fertilizer, much of it little more than snake oil. The need for an institution to test different chemical fertilizers to assess their value became evident to some, while others became convinced that only the traditional fertilizers of their peasant ancestors would ever work.. These two sides would continue to fight, with each other directly, and indirectly through their politicians, for the rest of the century.(K1)
Until the Civil War no federal initiative to invest in agricultural research had been undertaken due to territorial disputes between the federal and state governments. The southern states were particularly set against the federal government taking the leadership role in agricultural experimentation, but when the south succeeded their votes no longer counted, and a series of bills were passed that became known as “Farmers’ Legislation.” One of these created what is now called the United States Department of Agriculture and another provided money for a nationwide system of agricultural colleges.
It took a number of bills to establish enough money to really make things happen, but between the 1862 Morrill Act and the 1887 Hatch Act, and lots of other political actions, there emerged a system where Land Grant Colleges (like my Oklahoma State University) administered a number of experimental farms (they call them experiment stations), taught college students, and provided public education in what used to be called the “extension service” but is now sometimes called “outreach.”(E1,K1) If you look at the logo for my college you will see a triangle, and this is meant to represent the three missions of our college: research, teaching, and extension.
Figure 1—Logo of agricultural college at Oklahoma State University
For an example of how government funded research can be more effective than voluntary efforts, consider what happened when West Virginia’s experiment station gave out free seed and planting information to farmers, and then asked them later for information on how well the seeds performed. If farmers complied it would provide a wealth of data on the performance of different crops throughout the state. Unfortunately, of the 708 farmers who took the seed, only 1 returned useful information and most (85%) did not even respond. This is why we needed experimental farms, rather than trying to coordinate lots of little experiments from many different farms.(K1)
Consider a few examples of how agricultural research has improved agricultural efficiency in the twentieth century.
Eggs
Before egg production became an “industry”, eggs were produced on many small farms, each having between 50 and 300 hens. Much about the farm may seem idyllic. Hens (called layers if used largely for egg production) were given shelter and plenty of room, up to four square feet per hen, compared to the 0.46 square feet they get today in cage egg systems. The hens were allowed free access to the outside—not so much for their enjoyment, but because farmers had little choice. Before the 1950s there was no farm feed that could supply all the hens’ nutrient needs, so they had to be let loose to secure these other nutrients (like certain vitamins, minerals, and amino acids) for themselves. Also, the hens needed sunlight for Vitamin D. Many of the hens were killed by predators. I once visited a free-range farm where the mortality rate is around 25%, and the farm didn’t have to worry about “spent hens” because they rarely lived to such an age.
General scientific work in nutrition coupled with controlled scientific experiments taught us how to make complete chicken feeds, so that layers could be kept in cages throughout their life and no longer needed sunlight. Farmers were taught by extension agents how to use trap cages where, when a hen came to her nest to lay an egg, it wouldn’t let her out until a farmer opened a door to record which hens are laying. This allowed farmers to determine which hens were most productive. Some eventually wondered why they would ever even let the hen out and all, and so they stopped, and the vast majority of layers in the U.S. were kept in cages, and have been ever since.
Egg production does take place in factory-like conditions, in that the farmer has considerable control over everything. They can even determine the exact color of the egg yolk by adding different supplements to their feed. They have learned to keep lights on in the barn longer and keep barns at a comfortable temperature to increase productivity. Much of this research was performed by experimental farms, and extension agents spread out about the country educating average farmers about these findings. Not all farmers paid a lot of attention to them. But the ones that did got survived, and got bigger, while the others went out of business.
Some do not like these cage egg systems, but regardless of what you think about them one cannot deny their productivity. In the 1930s one hen would produce around 153 eggs per year. Today that number is 250, and most of this improvement has been given to consumers in the form of lower egg prices.(N1)
Figure 2—Egg prices over time
Corn
Frederick William I (1688-1740) was a Prussian king with a particular affinity for tall people. He sought to create a military unit with the tallest men in Europe, and even developed breeding program where tall males and females were asked to procreate to create the next generation of giant soldiers. The breeding program didn’t work. Asking tall people to procreate didn't produce particularly tall people, and over time the height of each generation declined until it equalled that of the average European.
Similarly, farmers’ tried to create high-yielding corn varieties by planting the seeds of corn with particularly large ears. The Prussian king did not create giant soldiers, and farmers did not create giant corn.
Scientists would later learn that high-yielding corn was achieved not by breeding two high yielding plants, but two different varieties of high-yielding plants—what we call “hybrid” varieties. It would be hard to find a bigger technological leap in agriculture than the development of hybrid corn varieties. A hybrid variety simply refers to the mating of two different varieties of corn plants. Think of the Labradoodle, a mix between a Labrador Retriever and a Poodle, but replace the two dog breeds with two different corn varieties. The idea of deliberately raising hybrid plants started with Gregor Mendel in 1865, but it took some time for his ideas to be put into practice.
In 1919 a researcher at the Connecticut Agricultural Experiment Station developed the first commercial double-cross hybrid, using four inbred parents, which produced exceptionally high-yielding and healthy corn plants. The first of these varieties was made available in 1921, though it would take about fifteen years, and much groundwork on the behalf of extension agents, before farmers took them seriously, and from that point on corn yields surged upwards.(Y1)
To be sure, suspicions of “book farming” lingered in the minds of many farmers. As late as 1913, 44 percent of farmers in a national survey reported that experience alone was valuable. Still, as agriculture became more specialized, less self-sufficient, and more oriented to the market, those farmers who hoped to remain prosperous depended increasingly on the knowledge discovered by agricultural science.
—Kerr, Norwood Allen. 1987. The Legacy: A Centennial History of the State Agricultural Experiment Stations 1887-1987. University of Missouri-Columbia and the Missouri Agricultural Experiment Station. Page 64.
Although there are many other reasons for the increase in corn yields over time, due to better corn genetics, between World War II and today the number of labor hours needed to produce 100 bushels of corn fell from 100 to 2 hours..(C1)
Figure 3—U.S. corn production and yields over time
Broilers
Broilers are what we call chickens raised for meat. They were called broilers because people used to raise the same chicken varieties for eggs and meat. The females would be used for laying eggs and the males were raised until they were 1.5-2.5 lbs and then sold for meat. The chickens were so small you could split then and cook them by broiling. Chickens today are too large for broiler, you’ll just have a burnt outside and raw inside!
Even in 1913 there was a factory mentality toward raising broilers. They were typically placed in small, crowded, and dark rooms to minimize fighting and movement. Experts told farmers to, “Put the fowls in coops so small that they cannot turn around.”
The broiler sector really started becoming an industry soon after presidential candidate Herbert Hoover promised “A chicken in every pot.” A chicken was an indicator of prosperity, because it was more expensive than other meats at the time. After Georgia suffered agricultural difficulties in the 1920s they looked to broiler production to simulate and diversity their economy. The state government provided money to the University of Georgia to develop and help farmers implement new production methods. Georgia’s Department of Agriculture even helped people build hatcheries and develop better breeds of birds specifically suited for meat production.
Yet it wasn’t just the government using science for increased productive efficiency, the private sector has their own momentum. Let’s talk about their involvement in the broiler industry.
Private sector research
Once the fruits of basic science research became evident the private sector jumped into the game and made their own contributions to a more efficient agriculture. Food processors and retailers wanted farmers to improve their efficiency, produce more white meat per bird, and to produce a more consistent carcass. To encourage this, the retailer A&P (the Walmart of the 1940s) and the USDA partnered to host a Chicken of Tomorrow contest, where farmers submitted eggs and the A&P-USDA team would hatch and raise the chickens, doing everything possible to ensure all chickens were treated the same. The winners established a breeding business and their birds’ genetics were made available to all big broiler producers. These genetics, and the newly found understanding of how genetics can really boost efficiency, created the modern broiler which is nothing if not amazing. It took almost 5 lbs of feed to produce one pound of broiler in 1925; today it takes only 2 lbs.
Figure 4—Broiler productivity over time
The crowning achievement of private sector research in agriculture is biotechnology. Now, I know not everyone approves of GMOs, but one has to marvel that we are even able to do it. I mean, whoever thought we would be able to manipulate a single gene in an organism?
When you think of GMOs, you think of Monsanto. In the 1970s Monsanto became convinced that it might be possible to design plants that would exhibit certain traits, like a resistance to the herbicides that it sold, allowing a farmer to spray their pesticide Round Up all over a field, knowing it would kill everything except the crop. For over ten years scientists at Monsanto pursued general research into genetic modification without having to worry too much about producing a profitable product. Their efforts did not go unrewarded. Monsanto learned how to use bacteria to transport a gene from one organism into another. Then a new CEO came in 1984 and made his intentions clear when he said, “We are not in the business of the pursuit of knowledge; we are in the business of the pursuit of product.” It was time to turn general scientific research into specific product development.
The heat was on to produce a soybean resistant to the herbicide Round Up (or glyphosate). But where could they find an organism with that gene? It took two years of searching, but they finally found it in the garbage of one of their plants where Round Up was produced. There were decontamination ponds to treat the residues, and near those ponds they found a bacterium that had developed a resistance to Round Up. They would then figure out a way to get the gene from that bacteria, insert it into a soybean’s DNA, and in 1993 the Round Up Ready soybean was launched, then commercialized in 1996.(M1,R1) Other GM crops were developed about the same time, and the age of biotechnology became manifest. I feel quite comfortable saying no private sector research has had more influence over the path of agriculture than Monsanto’s work in biotechnology.
Figure 5—Adoption of genetically modified crops in U.S.
We shouldn’t think that the private sector only makes agriculture more efficient by new farm technologies. Wiser decisions about things like where to locate can enhance our food supply by just as much.
The modern feedlot sector emerged from the 1960s when aggressive cattlemen spent large amounts of time and research using computer programs (in the 1960s, mind you!) to determine the best location for a feedlot. The best land is a little hilly to help control runoff, but in a largely dry climate with moderate temperatures to keep cattle healthy and control flies. It should be relatively close to slaughter houses, an inexpensive source of grain and the like.(B1) As feedlots shifted away from where corn was grown and closer to areas with better weather, the improvement in cattle health was worth the higher cost of acquiring grain. This has led to cheaper beef and possibly better animal welfare.
As firms develop more sophisticated tools for making logistical decisions, food production became more efficient and cheaper—just like the logistics employed by Walmart has made the price of everything cheaper, and that of UPS has made shipping packages cheaper.
After Rachel Carson
Private and public investments into agricultural research and education have clearly borne fruit, allowing Americans to spend far less on their income on food than their forefathers. Because we spend so little on food we can afford fast cars, good health care, large houses, and expensive summer camps for kids. Even Santa Claus managed to produce more toys for boys and girls to open on Christmas morning.
Figure 6—Percent of U.S. disposable income spent on food
Most of the twentieth century was focused on improving agricultural productivity, but with Rachel Carson’s book Silent Spring made Americans confront the fact that pesticides may reduce the cost of food production but also poses a number of health harms. As her book led to the creation of the Environmental Protection Agency and the environmental movement, people became concerned not just with affordable food but also soil erosion, pesticide residues, and more recently, greenhouse gas emissions. From these concerns the organic food industry was borne. With their stomachs full Americanˆs hearts were extended to livestock, and they became increasingly insistent that livestock be raised without suffering—thus launching the animal rights movement.
Food as a source of nourishment is what economists call a private good, which roughly means the food impacts only the person eating it. Buy a hamburger at McDonalds and that hamburger belongs to you and you alone. The environmental and animal rights movements introduced a public good component of food. Soil erosion affects everyone, even future generations. If your hamburger produces greenhouse gas emissions those emissions affect everyone, so everyone has an vested interest in what you eat. A vegan may not eat meat, but they care about even animals they do not eat, so if they believe your Sausage McMuffin caused animals to suffer then the vegan herself is affected by your choice of food.
This new public dimension of food meant agricultural scientists could no longer focus on agricultural productivity alone. Certainly, we still seek to produce food at a lower cost, but we also endeavor to reduce soil erosion, make sure pesticide residues cause little harm, reduce the carbon footprint of food, and raise animals more humanely. Most every food problem today is being actively studied by scientists in order to improve food. Perusing the gallery of agricultural scientists at Oklahoma State University makes this evident.
Gallery of agricultural scientists at Oklahoma State University
Extension Specialist Warren Roberts (Department of Horticulture and Landscape Architecture)—regular and organic vegetables
When discussing agriculture we too often talk about grains and livestock, and neglect the fact that much of our food comes from vegetable production, but most every agricultural college will have researchers, teachers, and extension agents who focuses on vegatable production. This requires him to master a number of skills from irrigation, plant fertility, mulching, and herbicide use. Research is most fruitful when there are agents who communicate with the public about vegetable production, and that is the domain of people like Warren Roberts, who discusses organic vegetable production below.
Dr. Michelle Calvo (Department of Animal Science)—animal welfare
Perhaps you have seen the 2010 HBO movie Temple Grandin depicting the life of the professor with that name? Dr. Grandin helped launch the scientific field of animal welfare, a torch held proudly today by scientists like Dr. Calvo who are dedicated to helping us better understand the minds of cows, chickens, and pigs, so that we can provide them a better life as they are raised to provide us with food.
Dr. Brett Carver (Department of Plant and Soil Sciences)—wheat breeding and genetics
Dr. Carver proves that as the agricultural sciences have branched out into new fields it has not forgotten its origins, or the importance of continually developing better varieties of crops like wheat. Oklahoma State University has an advanced breeding system where they develop new crop genetics and then test these new varieties in control experiments. It isn't all about productivity. Dr. Carver must send every new wheat variety through a series of tests to determine its gluten level, its protein content, its strength as a dough, and a variety of other indicators to determine where it best serves humans in their food supply.
Dr. Samuel Fuhlendorf (Department of Natural Resource Ecology and Management)—Range ecology
The last half-century has taught us that agriculture takes place within an ecological system, where all of nature is interconnected in complex ways. As new fertilization, pest control, and planting strategies are developed we must not only take into account how it affects a single farm but the entire ecosystem as well. Dr. Fuhlendorf specializes in the ecosystem of the range (where too little rainfall limits the ability of much besides grass to survive), where he educates us about the dynamics of fire on the range, how the soil changes in response to grazing, and the behavior of Lark sparrows on a prairie.
Interested in bugs? (Department of Entomology and Plant Pathology)
Pests are such a formidable problem in agriculture that OSU has a department called Entomology and Plant Pathology, where scientists develop better strategies for controlling insects and disease. The video below shows an interview with its department head regarding damage to alfalfa crops.
Undergraduates in the Department of Agricultural Education, Communications, and Leadership
It may surprise some that there is an agricultural communications department within many agricultural colleges, including Oklahoma State University. The video below describes a trip OSU undergraduates in agricultural took to Uganda, highlighting both the diversity of majors in agricultural colleges and the international opportunities available to students.
Dr. Jodi Campiche (Department of Agricultural Economics)—farm policy
Government policies are often so complex that people neither understand them nor know how to best react to policy changes. Dr. Campiche specializes in agricultural policy, with a particular focus on helping farmers understand the farm bill.
Michael Holmes ((Department of Horticulture and Landscape Architecture))—landscape architecture and sensory gardens
For students more interested in art and aesthetic design can still feel at home in an agricultural college, as we not only award degrees in landscape architecture but play an active role in in educating the public about creating the creation and nurturing of beauty.
)Dr. Ray Huhnke (Department of Biosystems and Agricultural Engineering)—renewable energy sources from agricultural biomass
Many readers have heard about corn ethanol, where corn is made into a fuel present in much of the U.S. gasoline supply. Because corn ethanol has not proved as advantageous as scientists initially hoped, researchers like Dr. Huhnke are searching for alternative forms of biofuel, like fuel made from plant cellulosic. Such biofuels are most valuable if some of the by-products can be fed to livestock, and part of his research is enhancing our ability to do just that.
Dr. Jayson Lusk (Department of Agricultural Economics)—consumer policy issues
Food is a controversial issue this days, and agricultural colleges have a social responsibility to actively participate in the dialogue of agriculture—s future. Dr. Lusk is perhaps the world's most known agricultural economist, who not only conducts research on consumer preferences for niche products like organic foods, but as the video below shows, engages the public to help them best understand reasons to purchase and not to purchase organic foods.
Dr. Ramanjulu Sunkar (Department of Biochemistry and Molecular Biology)—Use of molecular biology in improving switchgrass for bioenergy production
Dr. Chad Penn (Department of Plant and Soil Sciences)—soil and environmental chemistry
Learning how to produce more food with less environmental degradation requires a scientific understanding of the environment, particularly in regards to chemistry. Eastern Oklahoma recently confronted considerable water quality problems due to phosphorus runoff from farms, and Dr. Penn's research seeks to capture that phosphorus as it leaves the farm but before it enters rivers, discussed in the video below.
Dr. Dan Stein (Department of Animal Science—cattle breeding
It would be a mistake to think that agricultural colleges have branched out into new areas at the expense of traditional agriculture. Professors like Dr. Stein are continually seeking to educate farmers on how to care better for their cattle and improve beef and dairy productivity.
Dr. Jason Warren (Department of Plant and Soil Sciences)—soil management
With great interest in reducing greenhouse gas emissions has come the idea that by encouraging permanent plant growth on heavily tilled soils the plants will sequester carbon into the soil. Dr. Warren has conducted experiments to measure the extent to which carbon sequestration occurs.
Dr. Derrell Peel (Department of Agricultural Economics)—cattle marketing
Agricultural economics is also a science, a social science, and Dr. Peel applies the science of economics to help others understand cattle prices today and in the future.
References
(A1) Armstrong, Dorsey. 2009. The Medieval World [lectures]. Lecture 33: Science and Technology. The Great Courses. The Teaching Company.
(A2) Albala, Ken. Food: A Cultural Culinary History [lectures]. The Great Courses. The Teaching Company.
(B1) Billard, Jules B. February 1970. “The Revolution In American Agriculture.” National Geographic.
(C1) Chrystia Freeland. August 1, 2012. “The Triumph of the Family Farm.” The Atlantic.
(E1) Epplin, Francis M. 2012. “Market Failures and Land Grant Universities.” Journal of Agricultural and Applied Economics. 44(3):281-289.
(K1) Kerr, Norwood Allen. 1987. The Legacy: A Centennial History of the State Agricultural Experiment Stations 1887-1987. University of Missouri-Columbia and the Missouri Agricultural Experiment Station.
(M1) Monsanto. Roundup Ready Soybean [webpage]. Accessed December 13, 2013 at http://www.monsanto.com/weedmanagement/Pages/roundup-ready-system.aspx.
(M2) Martinez, Steve W. 2002. Vertical Coordination of Marketing Systems: Lessons From the Poultry, Egg, and Pork Industries. Economic Research Service. United States Department of Agriculture. Agricultural Economic Report No. 807.
(N1) Norwood, F. Bailey and Jayson L. Lusk. 2011. Compassion, by the Pound: The Economics of Farm Animal Welfare. Oxford University Press: NY, NY.
(P1) Paarlberg, Don and Philip Paarlberg. 2000. The Agricultural Revolution of the 20th Century. Iowa State University Press: Ames, IA.
(P2) Pollan, Michael. 2006. The Omnivore’s Dilemma: A Natural History of Four Meals. NY, NY: The Penguin Press.
(R1) Robin, Marie-Monique. 2008. The World According to Monsanto. Translated from French by George Holoch. The New Press: NY, NY.
(Y1) Yearbook of Agriculture. 1962. “Hybrid Corn.” Accessed December 13, 2013 at http://www.ars.usda.gov/is/timeline/corn.htm.
